"All rights reserved" is a phrase that originated in copyright law as part of copyright notices. It indicates that the copyright holder reserves, or holds for their own use, all the rights provided by copyright law, such as distribution, performance, and creation of derivative works; that is, they have not waived any such right. Copyright law in most countries no longer requires such notices, but the phrase persists. The original understanding of the phrase as relating specifically to copyright may have been supplanted by common usage of the phrase to refer to any legal right, although it is probably understood to refer at least to copyright.

In former times, the phrase was required as a result of the Buenos Aires Convention of 1910 which mandated that some statement of reservation of rights be made in order to secure protection in signatory countries of the convention. It was required to add the phrase as a written notice that all rights granted under existing copyright law (such as the right to publish a work within a specific area) were retained by the copyright holder and that legal action might be taken against infringement.

The requirement to add a notice became obsolete and essentially deprecated on August 23, 2000, as every country that was a member of the Buenos Aires Convention (which is the only copyright treaty requiring this notice to be used) is also a member of the Berne Convention which requires protection be granted without any formality of notice of copyright.

Since copyright law is neither straightforward nor widely understood in its details, nor is the Buenos Aires Convention's previous requirement and current deprecation of the phrase common lay knowledge, the phrase continues to hold popular currency and serve as a handy convention widely used by artists, writers and content creators to prevent ambiguity and clearly spell out the warning that their content is not up for grabs.